Pozzolanic Portland cementAs a result of combining up to 15 percent pozzolan (a material that contain active silica) with cement in the abrasion stage, the pozzolanic silica turns the useless materials (which are a cause of weakening the concrete's strength) into useful materials with high sticking ability, when mixing the cement with water. It will also decrease the heat created as the result of mixing the cement with water (this heat reduces the strength of the concrete). Therefore, since the hydration temperature must be low in building constructions, because of the high volume of concretes, or there is a high risk of erosion of concrete because of the proximity of sea water, using the pozzolanic cement for increasing the strength of the concrete is highly advised. However, as the initial strength of this kind of cement is lower than other type of cements and also the expansion time is higher than normal cements, it shouldn’t be used for projects which require fast strength and expansion.